diff options
| author | WANG Cong <xiyou.wangcong@gmail.com> | 2015-05-26 16:08:48 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-05-27 14:09:55 -0400 |
| commit | 86e363dc3b50bfd50a1f315934583fbda673ab8d (patch) | |
| tree | 0a55c306be0bd66f1218e527bbd0cbd31e3ad5a8 /net/sched/sch_api.c | |
| parent | ad0681185770716523c81b156c44b9804d7b8ed2 (diff) | |
net_sched: invoke ->attach() after setting dev->qdisc
For mq qdisc, we add per tx queue qdisc to root qdisc
for display purpose, however, that happens too early,
before the new dev->qdisc is finally set, this causes
q->list points to an old root qdisc which is going to be
freed right before assigning with a new one.
Fix this by moving ->attach() after setting dev->qdisc.
For the record, this fixes the following crash:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 975 at lib/list_debug.c:59 __list_del_entry+0x5a/0x98()
list_del corruption. prev->next should be ffff8800d1998ae8, but was 6b6b6b6b6b6b6b6b
CPU: 1 PID: 975 Comm: tc Not tainted 4.1.0-rc4+ #1019
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
0000000000000009 ffff8800d73fb928 ffffffff81a44e7f 0000000047574756
ffff8800d73fb978 ffff8800d73fb968 ffffffff810790da ffff8800cfc4cd20
ffffffff814e725b ffff8800d1998ae8 ffffffff82381250 0000000000000000
Call Trace:
[<ffffffff81a44e7f>] dump_stack+0x4c/0x65
[<ffffffff810790da>] warn_slowpath_common+0x9c/0xb6
[<ffffffff814e725b>] ? __list_del_entry+0x5a/0x98
[<ffffffff81079162>] warn_slowpath_fmt+0x46/0x48
[<ffffffff81820eb0>] ? dev_graft_qdisc+0x5e/0x6a
[<ffffffff814e725b>] __list_del_entry+0x5a/0x98
[<ffffffff814e72a7>] list_del+0xe/0x2d
[<ffffffff81822f05>] qdisc_list_del+0x1e/0x20
[<ffffffff81820cd1>] qdisc_destroy+0x30/0xd6
[<ffffffff81822676>] qdisc_graft+0x11d/0x243
[<ffffffff818233c1>] tc_get_qdisc+0x1a6/0x1d4
[<ffffffff810b5eaf>] ? mark_lock+0x2e/0x226
[<ffffffff817ff8f5>] rtnetlink_rcv_msg+0x181/0x194
[<ffffffff817ff72e>] ? rtnl_lock+0x17/0x19
[<ffffffff817ff72e>] ? rtnl_lock+0x17/0x19
[<ffffffff817ff774>] ? __rtnl_unlock+0x17/0x17
[<ffffffff81855dc6>] netlink_rcv_skb+0x4d/0x93
[<ffffffff817ff756>] rtnetlink_rcv+0x26/0x2d
[<ffffffff818544b2>] netlink_unicast+0xcb/0x150
[<ffffffff81161db9>] ? might_fault+0x59/0xa9
[<ffffffff81854f78>] netlink_sendmsg+0x4fa/0x51c
[<ffffffff817d6e09>] sock_sendmsg_nosec+0x12/0x1d
[<ffffffff817d8967>] sock_sendmsg+0x29/0x2e
[<ffffffff817d8cf3>] ___sys_sendmsg+0x1b4/0x23a
[<ffffffff8100a1b8>] ? native_sched_clock+0x35/0x37
[<ffffffff810a1d83>] ? sched_clock_local+0x12/0x72
[<ffffffff810a1fd4>] ? sched_clock_cpu+0x9e/0xb7
[<ffffffff810def2a>] ? current_kernel_time+0xe/0x32
[<ffffffff810b4bc5>] ? lock_release_holdtime.part.29+0x71/0x7f
[<ffffffff810ddebf>] ? read_seqcount_begin.constprop.27+0x5f/0x76
[<ffffffff810b6292>] ? trace_hardirqs_on_caller+0x17d/0x199
[<ffffffff811b14d5>] ? __fget_light+0x50/0x78
[<ffffffff817d9808>] __sys_sendmsg+0x42/0x60
[<ffffffff817d9838>] SyS_sendmsg+0x12/0x1c
[<ffffffff81a50e97>] system_call_fastpath+0x12/0x6f
---[ end trace ef29d3fb28e97ae7 ]---
For long term, we probably need to clean up the qdisc_graft() code
in case it hides other bugs like this.
Fixes: 95dc19299f74 ("pkt_sched: give visibility to mq slave qdiscs")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_api.c')
| -rw-r--r-- | net/sched/sch_api.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index ad9eed70bc8f..1e1c89e51a11 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -815,10 +815,8 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent, if (dev->flags & IFF_UP) dev_deactivate(dev); - if (new && new->ops->attach) { - new->ops->attach(new); - num_q = 0; - } + if (new && new->ops->attach) + goto skip; for (i = 0; i < num_q; i++) { struct netdev_queue *dev_queue = dev_ingress_queue(dev); @@ -834,12 +832,16 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent, qdisc_destroy(old); } +skip: if (!ingress) { notify_and_destroy(net, skb, n, classid, dev->qdisc, new); if (new && !new->ops->attach) atomic_inc(&new->refcnt); dev->qdisc = new ? : &noop_qdisc; + + if (new && new->ops->attach) + new->ops->attach(new); } else { notify_and_destroy(net, skb, n, classid, old, new); } |